<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" type="text/css" href="../demo.css">
    <!-- rel="stylesheet"引入的文件是样式表 -->
    <!--type="text/css"目录：text/css"  -->
    <!--文件名：href="demo.css"  -->
</head>
<body>
    <p>我爱你，世界！</p>

</body>
</html>